In general, an Al alloy casting is formed in a mold including a cavity and a feeder head cavity. Thus, the formed Al alloy casting includes a product corresponding to the cavity and a feeder head corresponding to the feeder head cavity. The feeder head is eventually cut off from the product. For example, a cylinder head, cylinder blocks, etc., of an engine are casted as the product.
The formed Al alloy casting (i.e., the product and the feeder head) is subjected to quenching (solution quenching) and aging in this order to increase the mechanical strength.
In view of facility, conventional quenching is performed by putting (sinking) the Al alloy casting formed in the mold into stored water.
The quenched and cooled Al alloy casting is placed in a furnace whose temperature is maintained higher than the temperature of the Al alloy casting, thereby aging the Al alloy casting. This requires futile work of heating the quenched and cooled Al alloy casting. There is thus a need to simplify the process of the aging.
PATENT DOCUMENT 1 discloses a method of quenching an Al alloy casting including a feeder head and a product to artificially age the Al alloy casting. The product of the Al alloy casting is selectively quenched and cooled (where the product is the cylinder head of an engine, the surface of the cylinder head at the combustion chamber is quenched and cooled by water spray). On the other hand, the feeder head is maintained at a relatively high temperature. When the product is cooled to a temperature range for artificial aging or a lower temperature, the quenching is interrupted to artificially age the product with the residual heat flowing from the relatively hot feeder head.
PATENT DOCUMENT 2 discloses the following. After casting in a mold including a sand mold forming a feeder head cavity, and a metal mold forming part of a cavity, the metal mold is separated. The surface of the casting (where the product is the cylinder head of an engine, the surface of the cylinder head at the combustion chamber) exposed by the separation touches a cooling medium to quench the casting. Then, the casting is covered by the sand mold and a heat insulating material to age the entire casting with the potential heat of the feeder head.